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EPS (extracellular polymeric substance) production is a self-protection mechanism by which microorganisms slow or eliminate adverse effects in unfavorable environments. In this study, Pseudomonas aeruginosa and Alcaligenes faecalis were selected to explore changes in EPS components, especially protein components, under stress caused by different concentrations of Cd(II). The results showed that the protein content in EPS was the highest. The two strains achieved maximum EPS production levels of 109.17 and 214.96 mg/g VSS at Cd(II) stress concentrations of 20 and 50 mg/L, which were increased by 52.07% and 409.69% compared with the levels exhibited before stress, respectively. The protein content correlated very well with data from adsorption experiments. Furthermore, FTIR, 3D-EEM, and XPS results illustrated that after Cd(II) stress, C-N, C=O/-COOH, and R-NO

In order to develop surfactant-enhanced remediation for nitrogen heterocyclic compounds (NHCs) (aniline, indole, and quinolone), the solubilization properties of micellar solutions of five surfactants, namely sodium dodecyl sulfate (SDS), rhamnolipid (RL), polysorbate (Tween 80), sorbitan monolaurate (Span 20), and iso-octyl phenoxy polyethoxy ethanol (TX-100) were investigated in this work. The solubilization capacities were quantified using critical micelle concentration (CMC) as well as thermodynamic and kinetic experiments. Besides, nuclear magnetic resonance (1H NMR) spectra were used to infer the locus of NHCs solubilized by SDS and TX-100. The results from the properties of five surfactants indicated that CMC was affected by temperature, while the micellization was spontaneous and could be both endothermic and exothermic based on the type of surfactant and temperature. Furthermore, the difference in compensation temperature was caused by different solubilization mechanism for various surfactants. The solubilization results showed that the solubilization of NHCs in the surfactant solutions followed a pseudo-first-order kinetic model. Meanwhile, the change in proton’s chemical shift depended on the structure of NHCs and the solubilization ability of surfactants. Finally, the orthogonal experiment (L16(43)) was elementarily designed to optimize the solubilization conditions of indole and the results showed that RL could be a better choice for solubilizing NHCs.

A strict aerobic Acinetobacter baumannii YNWH 226, isolated from an activated sludge reactor treating textile wastewater, was able to grow on Congo red as the sole carbon source under aerobic conditions. The decolorization and TOC reduction efficiency were 99.1 and 93.72%, respectively. The effects of the Congo red concentration were studied. The environmental factors (i.e., pH, temperature and agitation speed) on the biodegradation of Congo red in aqueous phase were studied and evaluated using response surface methodology. The results indicated that when the Congo red concentration was 100 mg/L, the optimal decolorization conditions were as follows: 37°C, pH 7.0 and 180 rpm. The single A. baumannii YNWH 226 was able to form aromatic amines by reductive breakage of the azo bond and then oxidize them into non-toxic metabolites.